from typing import Any

a=list(input("请输入一个排序数组:"))
b=eval(input("请输入一个目标值:"))
#左指针
left=0
#右指针
right=(len(a)-1)
for i in range(left,right):
    mid=(right-left)/2
    if a[i]==a[mid]:
        pass
        # return mid #函数才可以返回
    elif a[i]>mid:
        left=mid-1
        mid=(right-left)/2
    elif a[i]<mid:
        right=mid+1
        mid=(right-left)/2